1. Field of the Invention
The present invention generally relates to a method for determining the parameter values of an induction machine and, more particularly, to a method for determining the parameter values of an induction machine by means of polynomial calculations.
2. Description of the Related Art
Induction machines have been widely used for industrial control purposes. For example, a three-phase induction machine uses a three-phase winding as the stator, and the rotor does not require a circuit that generates direct current (DC) magnetic field. In this regard, the voltage, current and rotational torque of the rotor can be generated under the relative rotation between the stator and the rotor. In the above, the structure of the induction machine is simple and the operation thereof is convenient. Thus, the induction machines have become the commonly used alternating current (AC) electric motors. In the precision control technology, the induction machines not only provide the required power for the associated apparatuses but also serve a main role in controlling said apparatuses.
A conventional method for controlling an induction machine needs to be perform via an equivalent model (such as a steady state model and a dynamic state model). There are two approaches in determining the parameter values of the induction machine, which are off-line parameter determination and on-line parameter determination. In the off-line parameter determination, the parameter values of the induction machine are determined in an off-line mode of the induction machine. An example of off-line parameter determination is the standard IEEE 112 test which determines the parameter values of an equivalent circuit of the induction machine via a stator DC test, a lock-rotor test and an off-load starting test. On the other hand, in the on-line parameter determination, the associated equipment and controller are required, and the DC signals are used to determine the resistance of the stator via a self-adjusted procedure when the induction machine is on-load. Other parameter values of the induction machine can be determined.
However, some problems will be encountered when determining the parameter values of the induction machine. Specifically, it is inevitable that the signals always contain noise, which affects the calculation accuracy of the parameter values. In addition, the actual system is much more complex than the linear mode, adversely resulting in an error. In light of this, a larger number of times of iteration operations can be used to solve the above problems. However, this requires an initial value, and the calculation complexity is high. As such, the calculated result may be in a local optimum rather than an optimal solution.
In light of this, it is necessary to improve the conventional method by eliminating the use of the initial value and by reducing the calculation complexity.